The present invention relates to a slip anchor for a seat belt device, more particularly relates to a slid anchor for a seat belt device secured to an upper portion of a pillar of a vehicle body in order to guide a webbing extending from a take-up device of the seat belt device to a desired direction.
At present, the seat belt device is indispensable for a motor vehicle or the like in order to assure the passenger's safety because the device restrains the passenger from sudden movement caused by an acceleration or a shock by a collision.
This kind of seat belt device is comprised basically of a webbing (hereinafter, a webbing denotes a woven belt made of typical fiber materials of 50 mm width and prescribed by Japanese Industrial Standard in the specification), a retractor (hereinafter, ELR: Emergency Locking Retractor is denoted instead of a retractor) for locking withdrawal of the webbing at the time of a shock by the collision in order to restrain the passenger while retracting the webbing by a spring, a buckle device provided at a suitable position so as to fasten the webbing, a tongue, an anchor and the like.
As for the anchor, there are provided two anchors, e.g. a fixing anchor to fix an end of the webbing of a lad belt (a waist belt) on a floor of the vehicle and a slip anchor provided at an upper portion of a pillar of the vehicle by a fixing bolt or the like. The slip anchor pivots around the fixing bolt.
This slip anchor guides the webbing to change the direction of the webbing extending upward along the pillar from the ELR fixed to the pillar and located at the side position of the passenger to a front position of the passenger so as to work as a shoulder belt.
Additionally, in general, the slid anchor guides the webbing extending from the ELR to the shoulder belt position when the seat belt device is in use, or works to guide the shoulder belt to be wound in the ELR when not in use. It supports about a ton of force acting through the webbing by restraining and catching a passenger moved forward by an inertia force in case of a collision.
Therefore, the slip anchor must have a guide portion which guides the webbing smoothly in a freely movable manner and must be fixed firmly to the fixing portion such as a vehicle frame so as to withstand the force of the collision as well as the member itself must have a structure not to deform.
A slip anchor according to a conventional device is shown in FIG. 1A, in which the slip anchor 50 consists of a plate 51 formed by blanking a steel plate of prescribed thickness and a resin guide portion 53 formed by molding using a portion of the plate 51 as a core die.
The plate 51 is integrally formed of a fixing part 51A having a fixing hole 51a, and a guide part 51b having a guide opening 52, while the resin guide portion 53 having a circular cross section can smoothly guide the webbing W inserted into the guide opening 52 which has an elongated shape (Cf. FIG. 1B).
In addition, rounded portions 52a are provided at both ends of the guide opening 52 so as to prevent twisting or warping of the ends of the webbing when the webbing W is guided along the slip anchor.
In the slip anchor of this type, the guide portion and so on seen by a passenger are formed with resin to have a prescribed design in order to show quality impression. Also, because the plate 51 of the core part has a prescribed thickness, enough section modules to withstand the force of the collision is obtained by a steel section with a vertically elongated cross section.
A slip anchor according to another conventional device is shown in FIGS. 2A and 2B, in which a guide ring 62 made by bending a round steel rod into an elliptical shape in advance as shown in FIG. 2C is held in an end 61a, which is roll processed, of a fixing plate 61 for fixing a guide ring. At a pair of prescribed portions 61b, the ring 62 is fixed to the plate 61.
As is obvious from FIGS. 2A to 2C, there is provided a guide opening 63 into which the webbing W is inserted and guided with the guide ring 62 in the slip anchor 60.
Because the slip anchor of this type can be manufactured only by metal-working, the manufacturing cost can be reduced in comparison with the slip anchor shown in FIG. 1A, so that it is mainly used for a vehicle for business or the like.
Further, fixing parts are coated with resin covers C in all the slip anchors described above.
However, in the slip anchor as shown in FIG. 1A, it is made by an insertion molding, wherein the plate 51 which forms the core die at the resin molding must be buried at a prescribed position in advance, and is molded with resin.
Also, in general, a base metal is blanked in considering the material flow direction thereof at the portion 52a where a tensile force acts to obtain an enough strength in the plate 51.
Consequently, the manufacturing yield is low in each process, which causes a problem that the manufacturing cost increases.
Further, as for the slip anchors considering the cost as shown in FIG. 2A, not only the appearance is bad because a metal ring with an anti-corrosive coat is exposed, but also the section modules of the member is not enough because the guide portion where the webbing contacts is made by processing the round steel. Therefore, the material of the portion must have a large diameter not to deform by the acting power of the collision, which causes a problem that the manufacturing cost is not expected to reduce.